289. Just as every individual material substance is an expression of a state of vibration or type of energy to which all other substances react in greater or lesser degree, in the same way non-physical matter can be expressed as individual substances or types of energy to which other non-physical substances react to a greater or lesser degree. So, just as the science which deals with the reaction of physical substances is called "chemistry", then here in "Livets Bog", the science of the reaction of non-physical substances, and my account of it, will be called "cosmic chemistry".